For many years, the wool industry has tried to develop methods to reduce felting of wool which do not result in release of damaging substances to the environment. Recent developments have pointed towards low-temperature plasma treatment or the Delhey process as possible solutions to this problem.
Thus, it is known to treat wool fibre material with electrical gas discharges (socalled plasma), i.e. in a dry process. Plasma treatment provides a changed surface finish of the wool fibre which reduces the tendency to felt, improves the printability and accelerates the dyeability of the wool. The use of plasma treatment in textile finishing, especially in wool finishing, is highly advantageous, since the process potentially is an environmentally acceptable alternative to the conventional chlorination finishing processes, cf. Byrne, K. M. et al.: Corona discharge treatment of wool--commercial implications in DWI Report, (1992), vol. 109, p. 589-599, (Aachener Textiltagung 1991).
In textile finishing, the applicable plasma treatment is a low-temperature or unbalanced plasma treatment ("cold plasma" treatment), in particular the corona discharge treatment and glow discharge treatment, cf. Thomas, H. et al.: Environmentally friendly finishing processes for wool by pretreatment with electrical discharges in gas (plasma) in ITB vol. 2, 1993. The corona discharge treatment is carried out under atmospheric conditions and is a weak-current discharge providing an oxidation, and thereby a polarization, of the fibre surface. The glow discharge treatment is carried out under reduced pressure, i.e. producing electrons of higher energy than is possible in the corona discharge treatment, and may modify the fibre surface more intensively.
Accordingly, the plasma treatment provides to the wool or animal hair material reduced felting tendency and improved dying characteristics without the use of damaging chemicals and without wastewater (dry process). Also, the treatment provides improved shrink-proof properties to the treated material which, however, at present cannot meet the demands of the end-users. Furthermore, the treatment may reduce the soft handle of the wool or animal hair material.
Published Japanese Patent Application Tokkai Hei 4-327274 discloses a method for a shrink-proofing treatment of e.g. wool fibers by subjecting the fibers to a low-temperature plasma treatment followed by treatment with a shrink-proofing resin, e.g. block-urethane resin, polyamide epochlorohydrin resin, glyoxalic resin, ethylene-urea resin or acrylate resin, and then a weight reducing treatment with a proteolytic enzyme for obtaining a softening effect.
The Delhey process is described in DE-A-43 32 692 and in J. Delhey: PhD Thesis, RWTH Aachen (1994). In this process the wool is treated in an aqueous solution of hydrogen peroxide in the presence of soluble wolframate, optionally followed by treatment in a solution or dispersion of synthetic polymers, for improving the anti-felting properties of the wool, However, neither does this treatment meet the demands of the end-users.
It is the object of the present invention to provide a method for treating wool or animal hair material to obtain wool or animal hair material with reduced felting tendency, improved softness, increased whiteness, reduced pilling tendency and/or improved dyeing characteristics, in an easy and a purely biological way without the use of environmentally damaging chemicals or resins.